How do i Replace light bulbs on third brake light on 1998 ford explorer?

Answer 1

High Mount Stop Lamp

My Moms truck was rejected on the state inspection for a none working third taillight. After getting into the job I found you can not replace the bulbs . The unit is sealed and has a high-voltage neon tube powered by a "ballast" lower in the hatch door. If it does not work I would check the # 2 fuse on the fuse box. The circuit for the third brake light is separate from the right and left brake lights. If the fuse is not blown check to see if you have voltage at the connection at the light. You can access the connection by popping out 6 fasteners that hold the plastic interior panel in place. There are 2 screws in a step up transformer ballast ( unit is black has warning shock hazard on it). Take those 2 screws out and you should find a gray connector. Disconnect it. The test point is the green wire. Have a friend push the brake pedal and see if it will light up your test light. If the test light lights up then you have voltage to that point and that could mean the transformer or the light assembly may not be functioning properly. I have not found a way to test the transformer unit. What I did was reconnect the gray connector feeding voltage to the transformer and disconnected the light blue cable going to the light assembly put your red test lead from your volt meter to the short light blue cable coming out of the transformer and connect the black lead of your volt meter to the long light blue cable going to the light assembly. Make sure the volt meter is set to 750 AC volts.

A replacement light assembly or ballast can be purchased from salvage yards. LED replacement lights that do not require the ballast are available online for approximately $80.